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From: "pan2.li at intel dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c/109615] New: Redundant VSETVL after optimized code of RVV Date: Tue, 25 Apr 2023 01:07:22 +0000 [thread overview] Message-ID: <bug-109615-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109615 Bug ID: 109615 Summary: Redundant VSETVL after optimized code of RVV Product: gcc Version: 14.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: pan2.li at intel dot com Target Milestone: --- Assume we have a sample code as below. #include "riscv_vector.h" void f (int8_t * restrict in, int8_t * restrict out, int n, int m, int cond) { size_t vl = 101; if (cond) vl = m * 2; else vl = m * 2 * vl; for (size_t i = 0; i < n; i++) { vint8mf8_t v = __riscv_vle8_v_i8mf8 (in + i, vl); __riscv_vse8_v_i8mf8 (out + i, v, vl); vbool64_t mask = __riscv_vlm_v_b64 (in + i + 100, vl); vint8mf8_t v2 = __riscv_vle8_v_i8mf8_tumu (mask, v, in + i + 100, vl); __riscv_vse8_v_i8mf8 (out + i + 100, v2, vl); } for (size_t i = 0; i < n; i++) { vint8mf8_t v = __riscv_vle8_v_i8mf8 (in + i + 300, vl); __riscv_vse8_v_i8mf8 (out + i + 300, v, vl); } } Currently the upstream will generate the code as below with *-march=rv64gcv -O3 -frename-registers* options. It looks like the last vsetvl of .L4 bb is redundant. f: slliw a3,a3,1 bne a4,zero,.L2 li a5,101 mul a3,a3,a5 .L2: addi a4,a1,100 add t1,a0,a2 mv t0,a0 beq a2,zero,.L1 vsetvli zero,a3,e8,mf8,tu,mu .L4: addi a6,t0,100 addi a7,a4,-100 vle8.v v1,0(t0) addi t0,t0,1 vse8.v v1,0(a7) vlm.v v0,0(a6) vle8.v v1,0(a6),v0.t vse8.v v1,0(a4) addi a4,a4,1 bne t0,t1,.L4 addi a0,a0,300 addi a1,a1,300 add a2,a0,a2 vsetvli zero,a3,e8,mf8,ta,ma // <= redundant ? .L5: vle8.v v2,0(a0) addi a0,a0,1 vse8.v v2,0(a1) addi a1,a1,1 bne a2,a0,.L5 .L1: ret
next reply other threads:[~2023-04-25 1:07 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-04-25 1:07 pan2.li at intel dot com [this message] 2023-04-25 1:08 ` [Bug target/109615] " pinskia at gcc dot gnu.org 2023-05-05 13:18 ` cvs-commit at gcc dot gnu.org 2024-01-18 3:00 ` pan2.li at intel dot com 2024-01-20 17:23 ` pinskia at gcc dot gnu.org
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